The SEAL: Drowning Detection System

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The SEAL is a portable, water resistant monitoring and drowning detection system that decreases the risk of drowning for children.

According to the Center for Disease Control and Prevention (CDC) “Drowning is responsible for more deaths among children 1 to 4 than any other cause except congenital anomalies (birth defects). Among those, 1 to 14, fatal drowning remains the second-leading cause of unintentional injury-related deaths behind motor vehicle crashes.”

To offer an extra layer of protection, Raleigh, NC-based SEAL Innovation, Inc. has created the SEAL wearable swim monitor and drowning detection system that issues warnings and alarms to lifeguards and parents for swimmers in distress.

Graham E. Snyder, MD, and SEAL Innovation’s CEO, explains how the SEAL monitoring device is intended to be the last layer of defense for swimmers who are playing, learning to swim, doing laps, or diving at local swim spots and commercial pools. “A life guard cannot keep track of everything. They’re doing the best they can, but every once in a while they miss. It just baffles me that no one has gone after this problem more aggressively."

According to Snyder, the one thing that will save lives is parental and lifeguard vigilance. With the SEAL device, parents and guards are provided with a last layer of defense.

Main Components

The system contains three main components: the hub, swim bands, and a unique electronic signature. The hub is basically a wireless router that creates a virtual safety network between swimmers, guards, and parents. The swim bands are worn by the children, parents, and lifeguards; and they continuously receive and transmit signals to the hub regarding a swimmer’s status. The electronic signature is customized to each individual child’s age and level of skill. It provides the ability to simultaneously monitor multiple swimmers.

The band can be set to four levels (non-swimmer, beginner, advanced, and expert) providing an immersion alarm for beginner and non-swimmers, and a safeguarding component for elite swimmers and triathletes.

The SEAL swim bands use Wi-Fi technology and are FCC compatible. A big design challenge for the team was creating a product that worked when wet, which Snyder claimed was not a simple task. “Our biggest challenge and biggest victory was finding an antenna that could function in both Wi-Fi and direct RF transmission in harsh environments. Kids break things, and smear stuff on things like sand and sunscreen. They also jump up and down, and all these things needed to be considered and optimized in order for the SEAL to function properly.”

Users also have the capability to connect their mobile devices to the hub and program the skill level of each swimmer so the data from that swimmer’s band can be available at any time. This particular data can be used to optimize pool protocols and help to extend the safety of certain swimming environments.

Monitoring Submergence

For a distress alarm to be triggered, the swimmer wearing the SEAL swim band must be continuously submerged for a period of time that is longer than physiologically compatible with voluntary breath holding. “If a child is under water beyond what our tests have shown as normal breath holding, then an alarm is triggered,” says Snyder.

“What we’ve done through basic research is determine the reasonable times of which a child can voluntarily hold his/her breath according to their age, and we’ve also determined the reasonable times in which a child drowning can be rescued.”

Another challenge the design team faced was making sure the device functioned accordingly and appropriately; for example, the band must always trigger an alarm if a child is drowning, but never go off if a child is participating in activities associated with normal play. The antenna keeps track of how the radio frequency attenuation, which shows the submergence depth, and determines if an alarm should be triggered.

According to Snyder, if the system detects a swimmer in distress, interim warnings followed by a high-intensity audio, visual, and vibrating alarm are triggered on the swimmer’s, lifeguard’s, and parent’s bands as well as the central hub. Warnings and full-alert alarms are also activated in the event of power failure, out-of-range signal failure, or if a swimmer has unclasped his/her band.

“Once in warning or alarm state, the SEAL system requires the applicable swimmers to tap the central hub, close the loop, and confirm all is well. Every device in the system is aware of, and will report the absence of any other device, making the SEAL a fault-tolerant and fail-safe device that helps parents and lifeguards detect and respond to threatened drownings better than they can today,” says Snyder.

Design Optimization

To optimize the functionality of the SEAL monitoring device, the team had to consider many different elements; such as selecting materials that make it light and unnoticeable, as well as robust and durable. “We also had to consider the battery and power consumption, so we chose a rechargeable lithium-ion battery that lasts a minimum of six hours,” says Snyder.

The team experimented with various plug-in charging systems, as well as inductive charging, to help comply with the water resistant requirements.

For the SEAL to accurately monitor the status of a swimmer, both the lifeguard and the parent wearing the swim bands need to be within a 270-foot radius from the hub. Minimizing the amount of false alarms is vital to the SEAL’s success, and in helping to decrease the amount of accidental drowning deaths.

“With the SEAL system, swimmers can play, jump, dive, and even hold their breath, remaining safe in the water while wearing a comfortable, wireless swim band,” concludes Snyder.